ABSTRACT

Volcaniclastic diamictons, while found in all ancient and modern volcanic settings across New Zealand, are most commonly associated with stratovolcanoes. Lahar refers to a volcanic mass flow that consists of variable amounts of water and particles of different-sized volcanic lithologies; such flows can exhibit a range of rheologies that rapidly change at temporal and spatial scales. At Mt. Taranaki time packages of lahar deposits were originally grouped into chronostratigraphic formations, such as the 22,500–11,000 yrs B.P. Warea Formation, which consists of lahar deposits that display a range of sediment-water interactions reflecting variable rheological regimes. In historic times, lahars have been rare at Mt. Taranaki with the most recent events occurring in 1999 and 2008. In contrast, Mt. Ruapehu has been extremely active over the last 170 years with regular small-volume eruption-induced events and larger, more significant Crater-Lake breakout lahars. The Onetapu Formation comprises flows of the last 2,000 years that are 1–2 orders of magnitude greater in volume, stage and discharge. To better understand the hazard potential of such events, a range of numerical modelling and simulations have been created, with computational simulations being applied to hindcast and forecast the potential hazards of lahars from New Zealand’s stratovolcanoes.

摘要

虽然在新西兰所有古代和现代火山环境中都发现了火山碎屑双歧管，但最常见的是与层状火山有关。Lahar 是指由不同数量的水和不同大小的火山岩性颗粒组成的火山质量流；这种流动可以表现出一系列在时间和空间尺度上迅速变化的流变学。在山 塔拉纳基火山岩沉积物的时间包最初被分为年代地层地层，例如 22,500-11,000 年的 BP Warea 地层，该地层由火山岩沉积物组成，这些沉积物显示出一系列反映可变流变机制的沉积物-水相互作用。在历史时期，山上的火山泥流很少见。塔拉纳基最近的事件发生在 1999 年和 2008 年。相比之下，山。鲁阿佩胡在过去的 170 年里一直非常活跃，有规律的小体积喷发引发的事件和更大、更重要的火山口湖爆发火山灰。Onetapu 地层包含过去 2,000 年的流量，在体积、阶段和流量上都高出 1-2 个数量级。为了更好地了解此类事件的潜在危害，已经创建了一系列数值建模和模拟，并将计算模拟应用于后报和预测来自新西兰层状火山的火山泥流的潜在危害。